Aflatoxin and other mycotoxins commonly contaminate grains and other foods and may be carcinogenic, teratogenic, acutely toxic or otherwise hazardous to health. It is known that both adult animals and their young are susceptible to these agents. Therefore, these studies will examine the proposition that prenatal exposure to mycotoxins presents serious health consequences. The teratogenic potential of mycotoxins and the importance of placental transfer of these compounds in the teratogenic process will be examined. Mechanisms of teratogenicity will be examined to develop a better understanding of the events leading to malformations. Binding of the mycotoxins (or metabolites) in fetal tissues will be examined. Investigations will be undertaken to determine metabolic alterations such as changes in enzyme activity produced by these compounds. With this, knowledge of the causal chain of events leading to birth defects or illness can be examined. The metabolic reactions which modify the toxicity of these environmental toxins and their effect on the mechanism of toxicity can then be considered. It is only by knowing the mechanism of toxicity and/or teratogenicity that an intelligent approach to eliminating or, at least, decreasing toxic hazards can be undertaken.